Figure 4 Cartesian Coordinate Plot of Radioactive Decay
of Strontium 90
If the same data, the decay of strontium 90, is plotted on semi-log, the resulting plot (Figure 5)
will be a straight line. This is because the decay of radioactive material is an exponential
function. The resulting straight line of the semi-log plot allows a more accurate extrapolation
or interpolation of the data than the curve obtained from the cartesian plot.
For graphs in which both of the quantities (x,y) vary as a power function, a log-log plot is
convenient. A log-log plot is obtained by using logarithmic scales for both axes. Table 2 gives
data on the frequency of electromagnetic radiation as a function of the wavelength of the
radiation. Figure 6 is a log-log plot of the data given in Table 2.